Re: -> Red color and JPG???

Discussion in 'Digital Photography' started by Ray Fischer, Mar 30, 2010.

  1. Ray Fischer

    Ray Fischer Guest

    Steve JORDI <> wrote:
    >Hi,
    >I tried to find an explanation on the web but without success.
    >
    >Does anybody know why the red color looks so ugly when a digital
    >picture is saved as JPG?
    >It looks like it's the only dominant color that gets very pixelated
    >and grainy.
    >The cause of this artefact?


    Most indoor lighting is very red.

    --
    Ray Fischer
     
    Ray Fischer, Mar 30, 2010
    #1
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  2. Ray Fischer

    Peter Guest

    "Mike Russell" <> wrote in message
    news:...
    > Steve JORDI <> wrote:
    >>Hi,
    >>I tried to find an explanation on the web but without success.
    >>
    >>Does anybody know why the red color looks so ugly when a digital
    >>picture is saved as JPG?

    >
    > This is not always the case. Usually the blue channel is the weakest of
    > the three - more noise and less shadow detail.
    >
    >>It looks like it's the only dominant color that gets very pixelated
    >>and grainy.
    >>The cause of this artefact?

    >
    > It's hard to answer this without seeing an image that demonstrates what
    > you
    > are saying. There could be several reasons for a poor quality red
    > channel:
    >
    > 1) lighting - skylight is strong in blue, weakest in red, and could cause
    > noise and jpeg artifacting, which matches some of what you are describing
    > 2) exposure - saturated red objects, roses being an example, often blow
    > out
    > the red channel, resulting in orange or yellow areas with little detail



    Mike, thanks for the explanation of my issues shooting red flowers.
    Do you have any suggestions for a cure?



    --
    Peter
     
    Peter, Apr 3, 2010
    #2
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  3. Ray Fischer

    Peter Guest

    "Mike Russell" <> wrote in message
    news:dwng21qp3i5x$...
    > On Sat, 3 Apr 2010 15:32:01 -0400, Peter wrote:
    >
    >> "Mike Russell" <> wrote in message
    >> news:...
    >>> Steve JORDI <> wrote:
    >>>>Hi,
    >>>>I tried to find an explanation on the web but without success.
    >>>>
    >>>>Does anybody know why the red color looks so ugly when a digital
    >>>>picture is saved as JPG?
    >>>
    >>> This is not always the case. Usually the blue channel is the weakest of
    >>> the three - more noise and less shadow detail.
    >>>
    >>>>It looks like it's the only dominant color that gets very pixelated
    >>>>and grainy.
    >>>>The cause of this artefact?
    >>>
    >>> It's hard to answer this without seeing an image that demonstrates what
    >>> you
    >>> are saying. There could be several reasons for a poor quality red
    >>> channel:
    >>>
    >>> 1) lighting - skylight is strong in blue, weakest in red, and could
    >>> cause
    >>> noise and jpeg artifacting, which matches some of what you are
    >>> describing
    >>> 2) exposure - saturated red objects, roses being an example, often blow
    >>> out
    >>> the red channel, resulting in orange or yellow areas with little detail

    >>
    >>
    >> Mike, thanks for the explanation of my issues shooting red flowers.
    >> Do you have any suggestions for a cure?

    >
    > One technique that deals well with this is channel mixing. The idea is to
    > take information from the green and/or blue channels and mix it in with
    > the
    > red channel. If it's done right, you'll see detail in the blown out
    > areas.
    >
    > Dupe the image to a new layer and set it's mode to luminance. Use curves
    > on the blue and/or green layers to bump the contrast, and voila - detail
    > in
    > the blown out red areas.
    >
    > Apply image can be used in a similar way.
    >
    > The roses are starting to bloom in my neck of the woods, and I'll consider
    > doing a video tutorial on how to do this.



    I am looking forward to it. Meanwhile, I am playing with your suggestion
    using levels, since I am not very comfortable using curves. Yes, I
    understand you can get a lot more control with curves and I will try it.
    BTW, I should have mentioned I do all my shooting in raw

    --
    Peter
     
    Peter, Apr 4, 2010
    #3
  4. Ray Fischer

    Peter Guest

    "Savageduck" <savageduck1@{REMOVESPAM}me.com> wrote in message
    news:2010040319293137709-savageduck1@REMOVESPAMmecom...
    > On 2010-04-03 18:06:19 -0700, "Peter" <> said:
    >
    >> "Mike Russell" <> wrote in message
    >> news:dwng21qp3i5x$...
    >>> On Sat, 3 Apr 2010 15:32:01 -0400, Peter wrote:
    >>>
    >>>> "Mike Russell" <> wrote in message
    >>>> news:...
    >>>>> Steve JORDI <> wrote:
    >>>>>> Hi,
    >>>>>> I tried to find an explanation on the web but without success.
    >>>>>>
    >>>>>> Does anybody know why the red color looks so ugly when a digital
    >>>>>> picture is saved as JPG?
    >>>>>
    >>>>> This is not always the case. Usually the blue channel is the weakest
    >>>>> of
    >>>>> the three - more noise and less shadow detail.
    >>>>>
    >>>>>> It looks like it's the only dominant color that gets very pixelated
    >>>>>> and grainy.
    >>>>>> The cause of this artefact?
    >>>>>
    >>>>> It's hard to answer this without seeing an image that demonstrates
    >>>>> what
    >>>>> you
    >>>>> are saying. There could be several reasons for a poor quality red
    >>>>> channel:
    >>>>>
    >>>>> 1) lighting - skylight is strong in blue, weakest in red, and could
    >>>>> cause
    >>>>> noise and jpeg artifacting, which matches some of what you are
    >>>>> describing
    >>>>> 2) exposure - saturated red objects, roses being an example, often
    >>>>> blow
    >>>>> out
    >>>>> the red channel, resulting in orange or yellow areas with little
    >>>>> detail
    >>>>
    >>>>
    >>>> Mike, thanks for the explanation of my issues shooting red flowers.
    >>>> Do you have any suggestions for a cure?
    >>>
    >>> One technique that deals well with this is channel mixing. The idea is
    >>> to
    >>> take information from the green and/or blue channels and mix it in with
    >>> the
    >>> red channel. If it's done right, you'll see detail in the blown out
    >>> areas.
    >>>
    >>> Dupe the image to a new layer and set it's mode to luminance. Use
    >>> curves
    >>> on the blue and/or green layers to bump the contrast, and voila - detail
    >>> in
    >>> the blown out red areas.
    >>>
    >>> Apply image can be used in a similar way.
    >>>
    >>> The roses are starting to bloom in my neck of the woods, and I'll
    >>> consider
    >>> doing a video tutorial on how to do this.

    >>
    >>
    >> I am looking forward to it. Meanwhile, I am playing with your suggestion
    >> using levels, since I am not very comfortable using curves. Yes, I
    >> understand you can get a lot more control with curves and I will try it.
    >> BTW, I should have mentioned I do all my shooting in raw

    >
    > Peter,
    > If you are doing all your shooting in RAW, you should be able to make the
    > adjustments in ACR or whatever RAW converter you are using.
    > I am making the assumption you are dong more than White Balance
    > adjustments with ACR or your RAW converter.
    >
    > Just to check, here is ACR "White Balance" adjust panel;
    > http://homepage.mac.com/lco/filechute/ACR-WB-01.jpg
    >
    > Then "Camera Profile" panel;
    > http://homepage.mac.com/lco/filechute/ACR-Camera Profile-01.jpg
    >
    > and "Hue, Saturation & Luminosity" (HSL) panel;
    > http://homepage.mac.com/lco/filechute/ACR-HSL-01.jpg
    >
    > Those alone should give you what you need to make the adjustments to those
    > reds.
    >
    > There are all the other adjustment available in ACR, so give them a try.
    >



    I try to do as much as I can in ACR, except sharpening. My red problem is
    only with flowers. The problem with ACR is that it shifts all colors. Also,
    when I view the flower in the camera LCD it looks washed out even though the
    histogram shows proper exposure.

    Also,

    --
    Peter
     
    Peter, Apr 4, 2010
    #4
  5. Ray Fischer

    Peter Guest

    "Mike Russell" <> wrote in message
    news:...
    > On Sat, 3 Apr 2010 21:06:19 -0400, Peter wrote:
    >
    >> "Mike Russell" <> wrote in message
    >> news:dwng21qp3i5x$...
    >>> On Sat, 3 Apr 2010 15:32:01 -0400, Peter wrote:
    >>>
    >>>> "Mike Russell" <> wrote in message
    >>>> news:...
    >>>>> Steve JORDI <> wrote:
    >>>>>>Hi,
    >>>>>>I tried to find an explanation on the web but without success.
    >>>>>>
    >>>>>>Does anybody know why the red color looks so ugly when a digital
    >>>>>>picture is saved as JPG?
    >>>>>
    >>>>> This is not always the case. Usually the blue channel is the weakest
    >>>>> of
    >>>>> the three - more noise and less shadow detail.
    >>>>>
    >>>>>>It looks like it's the only dominant color that gets very pixelated
    >>>>>>and grainy.
    >>>>>>The cause of this artefact?
    >>>>>
    >>>>> It's hard to answer this without seeing an image that demonstrates
    >>>>> what
    >>>>> you
    >>>>> are saying. There could be several reasons for a poor quality red
    >>>>> channel:
    >>>>>
    >>>>> 1) lighting - skylight is strong in blue, weakest in red, and could
    >>>>> cause
    >>>>> noise and jpeg artifacting, which matches some of what you are
    >>>>> describing
    >>>>> 2) exposure - saturated red objects, roses being an example, often
    >>>>> blow
    >>>>> out
    >>>>> the red channel, resulting in orange or yellow areas with little
    >>>>> detail
    >>>>
    >>>>
    >>>> Mike, thanks for the explanation of my issues shooting red flowers.
    >>>> Do you have any suggestions for a cure?
    >>>
    >>> One technique that deals well with this is channel mixing. The idea is
    >>> to
    >>> take information from the green and/or blue channels and mix it in with
    >>> the
    >>> red channel. If it's done right, you'll see detail in the blown out
    >>> areas.
    >>>
    >>> Dupe the image to a new layer and set it's mode to luminance. Use
    >>> curves
    >>> on the blue and/or green layers to bump the contrast, and voila - detail
    >>> in
    >>> the blown out red areas.
    >>>
    >>> Apply image can be used in a similar way.
    >>>
    >>> The roses are starting to bloom in my neck of the woods, and I'll
    >>> consider
    >>> doing a video tutorial on how to do this.

    >>
    >>
    >> I am looking forward to it. Meanwhile, I am playing with your suggestion
    >> using levels, since I am not very comfortable using curves. Yes, I
    >> understand you can get a lot more control with curves and I will try it.
    >> BTW, I should have mentioned I do all my shooting in raw

    >
    > Levels is an inadequate tool. If you are in raw, try using highlight
    > recovery to get detail into the red flowers.



    Thanks for that suggestion. I agree that levels is inadequate for many
    tasks. I primarily use it for haze elimination and to give the shot a
    little more punch. I have a thing about not using presets, as each image is
    different. I can to some effective things with curves, but there is much
    more to learn. At this point I am waiting for CS5 for its context aware
    selections that I hope will help me with what I am trying to accomplish.

    --
    Peter
     
    Peter, Apr 4, 2010
    #5
  6. Savageduck wrote:
    > On 2010-04-03 20:39:36 -0700, "Peter" <> said:
    >
    >> "Savageduck" <savageduck1@{REMOVESPAM}me.com> wrote in message
    >> news:2010040319293137709-savageduck1@REMOVESPAMmecom...
    >>> On 2010-04-03 18:06:19 -0700, "Peter" <>
    >>> said:
    >>>
    >>>> "Mike Russell" <> wrote in message
    >>>> news:dwng21qp3i5x$...
    >>>>> On Sat, 3 Apr 2010 15:32:01 -0400, Peter wrote:
    >>>>>
    >>>>>> "Mike Russell" <> wrote in message
    >>>>>> news:...
    >>>>>>> Steve JORDI <> wrote:
    >>>>>>>> Hi,
    >>>>>>>> I tried to find an explanation on the web but without success.
    >>>>>>>>
    >>>>>>>> Does anybody know why the red color looks so ugly when a digital
    >>>>>>>> picture is saved as JPG?
    >>>>>>>
    >>>>>>> This is not always the case. Usually the blue channel is the
    >>>>>>> weakest of
    >>>>>>> the three - more noise and less shadow detail.
    >>>>>>>
    >>>>>>>> It looks like it's the only dominant color that gets very pixelated
    >>>>>>>> and grainy.
    >>>>>>>> The cause of this artefact?
    >>>>>>>
    >>>>>>> It's hard to answer this without seeing an image that
    >>>>>>> demonstrates what
    >>>>>>> you
    >>>>>>> are saying. There could be several reasons for a poor quality red
    >>>>>>> channel:
    >>>>>>>
    >>>>>>> 1) lighting - skylight is strong in blue, weakest in red, and
    >>>>>>> could cause
    >>>>>>> noise and jpeg artifacting, which matches some of what you are
    >>>>>>> describing
    >>>>>>> 2) exposure - saturated red objects, roses being an example,
    >>>>>>> often blow
    >>>>>>> out
    >>>>>>> the red channel, resulting in orange or yellow areas with little
    >>>>>>> detail
    >>>>>>
    >>>>>>
    >>>>>> Mike, thanks for the explanation of my issues shooting red flowers.
    >>>>>> Do you have any suggestions for a cure?
    >>>>>
    >>>>> One technique that deals well with this is channel mixing. The
    >>>>> idea is to
    >>>>> take information from the green and/or blue channels and mix it in
    >>>>> with the
    >>>>> red channel. If it's done right, you'll see detail in the blown
    >>>>> out areas.
    >>>>>
    >>>>> Dupe the image to a new layer and set it's mode to luminance. Use
    >>>>> curves
    >>>>> on the blue and/or green layers to bump the contrast, and voila -
    >>>>> detail in
    >>>>> the blown out red areas.
    >>>>>
    >>>>> Apply image can be used in a similar way.
    >>>>>
    >>>>> The roses are starting to bloom in my neck of the woods, and I'll
    >>>>> consider
    >>>>> doing a video tutorial on how to do this.
    >>>>
    >>>>
    >>>> I am looking forward to it. Meanwhile, I am playing with your
    >>>> suggestion using levels, since I am not very comfortable using
    >>>> curves. Yes, I understand you can get a lot more control with curves
    >>>> and I will try it.
    >>>> BTW, I should have mentioned I do all my shooting in raw
    >>>
    >>> Peter,
    >>> If you are doing all your shooting in RAW, you should be able to make
    >>> the adjustments in ACR or whatever RAW converter you are using.
    >>> I am making the assumption you are dong more than White Balance
    >>> adjustments with ACR or your RAW converter.
    >>>
    >>> Just to check, here is ACR "White Balance" adjust panel;
    >>> http://homepage.mac.com/lco/filechute/ACR-WB-01.jpg
    >>>
    >>> Then "Camera Profile" panel;
    >>> http://homepage.mac.com/lco/filechute/ACR-Camera Profile-01.jpg
    >>>
    >>> and "Hue, Saturation & Luminosity" (HSL) panel;
    >>> http://homepage.mac.com/lco/filechute/ACR-HSL-01.jpg
    >>>
    >>> Those alone should give you what you need to make the adjustments to
    >>> those reds.
    >>>
    >>> There are all the other adjustment available in ACR, so give them a try.
    >>>

    >>
    >>
    >> I try to do as much as I can in ACR, except sharpening. My red problem
    >> is only with flowers. The problem with ACR is that it shifts all
    >> colors. Also, when I view the flower in the camera LCD it looks washed
    >> out even though the histogram shows proper exposure.
    >>
    >> Also,

    >
    > In ACR have you tried the "targeted Adjustment Tool" from the toolbar in
    > conjunction with the HSL panel.
    > Select that tool, open HSL, pick H, S, or L click in the ajustment value
    > window. place the tool on the flower needing adjustment, and click &
    > drag to left or right to adjust the target.


    Depending on the version of ACR, you should be able to very fine tune
    reds, hues of reds, and saturation thereof.

    I happen to use Lightroom to do the same.

    --
    John McWilliams
     
    John McWilliams, Apr 4, 2010
    #6
  7. Ray Fischer

    Peter Guest

    "Savageduck" <savageduck1@{REMOVESPAM}me.com> wrote in message
    news:2010040321133822503-savageduck1@REMOVESPAMmecom...
    > On 2010-04-03 20:39:36 -0700, "Peter" <> said:
    >
    >> "Savageduck" <savageduck1@{REMOVESPAM}me.com> wrote in message
    >> news:2010040319293137709-savageduck1@REMOVESPAMmecom...
    >>> On 2010-04-03 18:06:19 -0700, "Peter" <>
    >>> said:
    >>>
    >>>> "Mike Russell" <> wrote in message
    >>>> news:dwng21qp3i5x$...
    >>>>> On Sat, 3 Apr 2010 15:32:01 -0400, Peter wrote:
    >>>>>
    >>>>>> "Mike Russell" <> wrote in message
    >>>>>> news:...
    >>>>>>> Steve JORDI <> wrote:
    >>>>>>>> Hi,
    >>>>>>>> I tried to find an explanation on the web but without success.
    >>>>>>>>
    >>>>>>>> Does anybody know why the red color looks so ugly when a digital
    >>>>>>>> picture is saved as JPG?
    >>>>>>>
    >>>>>>> This is not always the case. Usually the blue channel is the
    >>>>>>> weakest of
    >>>>>>> the three - more noise and less shadow detail.
    >>>>>>>
    >>>>>>>> It looks like it's the only dominant color that gets very pixelated
    >>>>>>>> and grainy.
    >>>>>>>> The cause of this artefact?
    >>>>>>>
    >>>>>>> It's hard to answer this without seeing an image that demonstrates
    >>>>>>> what
    >>>>>>> you
    >>>>>>> are saying. There could be several reasons for a poor quality red
    >>>>>>> channel:
    >>>>>>>
    >>>>>>> 1) lighting - skylight is strong in blue, weakest in red, and could
    >>>>>>> cause
    >>>>>>> noise and jpeg artifacting, which matches some of what you are
    >>>>>>> describing
    >>>>>>> 2) exposure - saturated red objects, roses being an example, often
    >>>>>>> blow
    >>>>>>> out
    >>>>>>> the red channel, resulting in orange or yellow areas with little
    >>>>>>> detail
    >>>>>>
    >>>>>>
    >>>>>> Mike, thanks for the explanation of my issues shooting red flowers.
    >>>>>> Do you have any suggestions for a cure?
    >>>>>
    >>>>> One technique that deals well with this is channel mixing. The idea
    >>>>> is to
    >>>>> take information from the green and/or blue channels and mix it in
    >>>>> with the
    >>>>> red channel. If it's done right, you'll see detail in the blown out
    >>>>> areas.
    >>>>>
    >>>>> Dupe the image to a new layer and set it's mode to luminance. Use
    >>>>> curves
    >>>>> on the blue and/or green layers to bump the contrast, and voila -
    >>>>> detail in
    >>>>> the blown out red areas.
    >>>>>
    >>>>> Apply image can be used in a similar way.
    >>>>>
    >>>>> The roses are starting to bloom in my neck of the woods, and I'll
    >>>>> consider
    >>>>> doing a video tutorial on how to do this.
    >>>>
    >>>>
    >>>> I am looking forward to it. Meanwhile, I am playing with your
    >>>> suggestion using levels, since I am not very comfortable using curves.
    >>>> Yes, I understand you can get a lot more control with curves and I will
    >>>> try it.
    >>>> BTW, I should have mentioned I do all my shooting in raw
    >>>
    >>> Peter,
    >>> If you are doing all your shooting in RAW, you should be able to make
    >>> the adjustments in ACR or whatever RAW converter you are using.
    >>> I am making the assumption you are dong more than White Balance
    >>> adjustments with ACR or your RAW converter.
    >>>
    >>> Just to check, here is ACR "White Balance" adjust panel;
    >>> http://homepage.mac.com/lco/filechute/ACR-WB-01.jpg
    >>>
    >>> Then "Camera Profile" panel;
    >>> http://homepage.mac.com/lco/filechute/ACR-Camera Profile-01.jpg
    >>>
    >>> and "Hue, Saturation & Luminosity" (HSL) panel;
    >>> http://homepage.mac.com/lco/filechute/ACR-HSL-01.jpg
    >>>
    >>> Those alone should give you what you need to make the adjustments to
    >>> those reds.
    >>>
    >>> There are all the other adjustment available in ACR, so give them a try.
    >>>

    >>
    >>
    >> I try to do as much as I can in ACR, except sharpening. My red problem is
    >> only with flowers. The problem with ACR is that it shifts all colors.
    >> Also, when I view the flower in the camera LCD it looks washed out even
    >> though the histogram shows proper exposure.
    >>
    >> Also,

    >
    > In ACR have you tried the "targeted Adjustment Tool" from the toolbar in
    > conjunction with the HSL panel.
    > Select that tool, open HSL, pick H, S, or L click in the ajustment value
    > window. place the tool on the flower needing adjustment, and click & drag
    > to left or right to adjust the target.
    >



    thanks, I still have a lot to learn

    --
    Peter
     
    Peter, Apr 4, 2010
    #7
  8. Ray Fischer

    Martin Brown Guest

    Peter wrote:
    > "Mike Russell" <> wrote in message
    > news:...
    >> Steve JORDI <> wrote:
    >>> Hi,
    >>> I tried to find an explanation on the web but without success.
    >>>
    >>> Does anybody know why the red color looks so ugly when a digital
    >>> picture is saved as JPG?

    >>
    >> This is not always the case. Usually the blue channel is the weakest of
    >> the three - more noise and less shadow detail.
    >>
    >>> It looks like it's the only dominant color that gets very pixelated
    >>> and grainy.
    >>> The cause of this artefact?

    >>
    >> It's hard to answer this without seeing an image that demonstrates
    >> what you
    >> are saying. There could be several reasons for a poor quality red
    >> channel:
    >>
    >> 1) lighting - skylight is strong in blue, weakest in red, and could cause
    >> noise and jpeg artifacting, which matches some of what you are describing
    >> 2) exposure - saturated red objects, roses being an example, often
    >> blow out
    >> the red channel, resulting in orange or yellow areas with little detail

    >
    >
    > Mike, thanks for the explanation of my issues shooting red flowers.
    > Do you have any suggestions for a cure?


    It would be a lot easier if you posted an example of the sort of
    problems you are encountering. Psychic remote viewing and guessing is
    not effective at judging photographs. A sample image would be invaluable
    here - preferably in PNG format showing the detail problem that you
    refer to.

    The smaller number of red photosites in a Bayer sensor means that
    resolution is degraded in the absence of any strong luminance contrast.
    But it should work OK for fine black detail on a red ground provided
    that you stick to raw an use a reputable converter. It is one example
    where the Foveon tricolour sensor would be beneficial.

    The JPEG images out of a normal digicam are already chroma subsampled
    2x1 and no current mainstream decoders reproduce that faithfully where
    high saturation red or blue colours are combined with black detail.

    Regards,
    Martin Brown
     
    Martin Brown, Apr 6, 2010
    #8
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